Edge-functionalized and substitutional doped graphene nanoribbons: electronic and spin properties

Graphene nanoribbons are the counterpart of carbon nanotubes in graphene-based nanoelectronics. We investigate the electronic properties of chemically modified ribbons by means of density functional theory. We observe that chemical modifications of zigzag ribbons can break the spin degeneracy. This promotes the onset of a semiconducting-metal transition, or of an half-semiconducting state, with the two spin channels having a different bandgap, or of a spin-polarized half-semiconducting state -where the spins in the valence and conduction bands are oppositely polarized. Edge functionalization of armchair ribbons gives electronic states a few eV away from the Fermi level, and does not significantly affect their bandgap. N and B produce different effects, depending on the position of the substitutional site. In particular, edge substitutions at low density do not significantly alter the bandgap, while bulk substitution promotes the onset of semiconducting-metal transitions. Pyridine-like defects induce a semiconducting-metal transition.Comment: 12 pages, 5 figure

Shortening the length of stay and mechanical ventilation time by using positive suggestions via MP3 players for ventilated patients

Long stay in intensive care unit (ICU) and prolonged ventilation are deleterious for subsequent quality of life and surcharge financial capacity. We have already demonstrated the beneficial effects of using suggestive communication on recovery time during intensive care. The aim of our present study was to prove the same effects with standardized positive suggestive message delivered by an MP3 player. Patients ventilated in ICU were randomized into a control group receiving standard ICU treatment and two groups with a standardized pre-recorded material delivered via headphones: a suggestive message about safety, self-control, and recovery for the study group and a relaxing music for the music group. Groups were similar in terms of age, gender, and mortality, but the SAPS II scores were higher in the study group than that in the controls (57.8 ± 23.6 vs. 30.1 ± 15.5 and 33.7 ± 17.4). Our post-hoc analysis results showed that the length of ICU stay (134.2 ± 73.3 vs. 314.2 ± 178.4 h) and the time spent on ventilator (85.2 ± 34.9 vs. 232.0 ± 165.6 h) were significantly shorter in the study group compared to the unified control. The advantage of the structured positive suggestive message was proven against both music and control groups

Felföldy Lajos (1920–2016)

Felföldy Lajos (1920–2016) magyar botanika és hidrobiológia egyik legsokoldalúbb és legeredetibb egyénisége volt. Pályáját Soó Rezső irányításával kezdte, 1938 és 1946 között aktívan részt vett a debreceni és 1941–1942 között a kolozsvári Tudományegyetem Növénytani Tanszékén folyó geobotanikai kutatásokban. Számos tudományterületen maradandót alkotott. A légszennyezésnek az epifiton zuzmókra gyakorolt hatását vizsgáló kutatásai (1942) világviszonylatban is az elsők közé tartoznak. A Raunkiaer-féle növényi életforma-rendszeren belül elkülönítette a kétévesek (Hemitherophyta) életforma-típusát az egyévesekétől (1942). Úttörő szerepet játszott Magyarországon a vadon élő növényfajok citológiai (kariológiai) vizsgálatában (1947–1949). Foglalkozott növényélettannal (1951–1959), vizekben folyó primer produkcióval és algatenyésztéssel (1958–1960). 1972-ban életre hívta és 1990-ig szerkesztette a Vízügyi Hidrobiológia sorozatot. Megalapozta a magyarországi vízminőség-védelmet, amely a mai napig meghatározza a magyar hidrobiológusok szemléletét. 14 és 89 éves kora között legalább tízezer herbáriumi lapot gyűjtött. Nyugdíjba vonulása után a MTM Növénytár és az ELTE Füvészkert herbáriumi anyagának rendezésével, revíziójával foglalkozott, aktívan részt vett az Új Magyar Füvészkönyv elkészítésének munkálataiban. Munkáira egyszerre jellemző a természet iránti mély tisztelet, az elméleti megalapozottság és a gyakorlatiasság.</jats:p

Sebum lipids influence macrophage polarization and activation

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Chemically active substitutional nitrogen impurity in carbon nanotubes

We investigate the nitrogen substitutional impurity in semiconducting zigzag and metallic armchair single-wall carbon nanotubes using ab initio density functional theory. At low concentrations (less than 1 atomic %), the defect state in a semiconducting tube becomes spatially localized and develops a flat energy level in the band gap. Such a localized state makes the impurity site chemically and electronically active. We find that if two neighboring tubes have their impurities facing one another, an intertube covalent bond forms. This finding opens an intriguing possibility for tunnel junctions, as well as the functionalization of suitably doped carbon nanotubes by selectively forming chemical bonds with ligands at the impurity site. If the intertube bond density is high enough, a highly packed bundle of interlinked single-wall nanotubes can form.Comment: 4 pages, 4 figures; major changes to the tex